Computer communications, like many other uses of computers, typically requires precise set up by a user. Before a task such as "send a message to the Chicago office" can be performed, much preparation is typically required, including the specification of various communication parameters. Such parameters might include the name of the particular Chicago computer system, an access password, its telephone number, the data rate at which its modem operates, and so forth.
The need for set up flows from the fact that communications systems are typically designed to be relatively flexible; they are designed to work with a range of different system configurations. Some configuration parameters can be automatically determined (e.g., the capabilities of a modem internal to the user's system). However, various aspects of a particular configuration to be used must be specified by a user.
The nature of the configuration information that a user must provide varies, depending upon the communications environment such as these examples: synchronous and asynchronous communications over switched lines can involve parameters such as data rate, telephone number, delay time between attempts to dial; network communications, both local area networks and wide area networks, can involve parameters such as system names and types, file transfer passwords, and system capabilities (e.g., types of transfers supported).